Variation & Adaptation Flashcards
Evolution
a permanent genetic change in a population.
Individuals CANNOT evolve over their lifetime (only populations evolve!)
Populations of the same species that are exposed to different environmental pressures can become so genetically different that they can no longer interbreed; they diverge (split) into two separate species!
Evolution can be thought of in multiple ways
-Change over time
-Change in heritable features over time within populations
-The origin of new forms of life (i.e. new species or subspecies)
-Descent with modification (descendents inherit their attributes from common ancestors) - proposed by Charles Darwin
Variation
give an individual a better chance of surviving to reproduce will be passed onto offspring.
Adaptation
As this trait is passed on through successive generations, the variation will become more and more common in the population.
Adaptations can be visible or invisible differences.
Interspecific Variation
variations occur between different species
Eg. humpback vs. orca
Intraspecific Variation
variations occur between members of the same species
Eg. ladybug spots
Continuous Variation
refers to characteristics like weight or height, which change gradually.
-No distinct categories (variation can exist on a spectrum)
-Controlled by many genes
-Strongly influenced by the environment
Eg. eye colour, hair colour, height, etc.
Discrete (Discontinuous) Variation
Distinct categories (this vs. that)
Controlled by a few genes
Unaffected by the environment
Eg. tongue rolling, blood type, etc.
Structural Adaptation
physical features of an organism
Eg. Teeth, feathers, scales, talons, shells, needles, etc.
Behavioural Adaptation
the way an organism acts or things it does to survive
Eg. hibernation, migration, play dead, etc.
Physiological Adaptation
changes or chemical reactions that occur within an organism
Eg. venom, poison, toxins, etc.
Sexual Reproduction
- Mixing of genetic information from the parents (male sperm and female egg)
- Sexual reproduction increases the variability in a population (makes the gene pool larger - which is a good thing!)
Mutations
Changes in the DNA of an organism. Can be caused by mutagens.
Eg, Color blindess, Sickle cell anemia
Natural Selection
Mechanism of evolution. Organisms that are more adapted to their environment are more likely to survive and pass on the genes that aided their success. This process causes species to change and diverge over time.
Phenotype
an observable trait, can refer to anything from a common trait, such as height or hair color, to presence or
Gradualism
Process of evolution takes place over MANY small steps. The world is much older than previously thought.
Overproduction
More organisms are produced than can survive due to limited resources - encourages competition
Population Speciation
Individuals within a population vary in their traits (variation), some of which are heritable. This causes very small changes within populations (adaptation), causing the evolution of that species
Jean-Baptiste Lamarck
-Believed individual organisms changed in response to their environment, then passed favourable traits to their offspring.
-Use and Disuse
Eg. Giraffes have long necks because they stretched them to reach leaves on tall trees, then passed these long necks to their offspring
Charles Darwin
Sailed on the HMS Beagle to Africa, South America, Australia, and the Galapagos Islands to do research.
Credited with the theory of natural selection or “survival of the fittest” which attempts to explain how populations evolve.
Descent with Modification
organisms are descended from one or more common ancestors
